42 / 28 = 1.5
Therefore if we multiply 35 by 1.5 it would be:
52.5
"Completing the square" is a step in the solution of quadratic equations. It can be accomplished without the guesswork or trial-and-error associated with methods like factoring, and it always leads to a solution. It is the method by which the quadratic formula is derived.
I think the answer is A.
It's probably wanting you to use pythagorean theorem.
